Economic aspects of setting the minimum flow for water power plants on Jizera river

There is an obligation to hold a minimal flow when running a water power plant in a current czech legistation. There are environmental reasons to determine the minimum discharge and the way to set it is not valid at the moment. We can see a difference in a type of water power stations when comparing the effects from electric power which is produced in water power plant situated on czech rivers and the damage that does not appear on the environment. The weir type of power plant harms the surroundings mildly except of the possible migration obstacles. But the derivation type makes loss that could be hardly compensate by the produced electricity. Different methods of evaluating the enrironment brinks various results and that is the reason why it is hard to say how much the effects from producing the electricity exceed the benefits arising from instream water or vice versa. The only conclusion that can be said is the advice about including more points of view when setting the minimum flowage.